RE Topology Report — Internet2 (AS11537)

How to read this page

This front page is a map of the AS paths Internet2 receives toward AS11537. Use it to find an AS, compare route counts, and open focused graphs for a network, prefix set, node set, or anycast subset.

The tree

AS is the AS at that position in the path. Rows with a triangle have more downstream ASes; selecting a row opens its route graph.
Accepted is the count of unique prefixes that traverse that AS and passed Internet2 import policy.
Rejected is the count of unique prefixes that traverse that AS but were filtered by policy.
LPP / metric bar summarizes the selected customer-cone metric. For family-split metrics the top bar is v6 and the lower bar is v4; ASPA is a single AS-level bar. The live Bar key under the metric controls explains the active colors. Click a bar to see exact counts for all six metrics.

Metrics

The Metric buttons change the tree's last column. Interesting-first reorders sibling ASes by the selected metric so the riskiest or most unusual cases float upward; Sort family chooses whether v4 or v6 drives that order for family-split metrics.

LPP: Local-preference probe outcome by address family. Green means R&E preferred, amber means AS-path determined, and rose means commodity preferred. Segment width is the share of responsive probed hosts.
More-specifics: Address-space share with DFZ more-specific routes not tagged as R&E. Green remains R&E-available; rose is traffic diverted by longest-prefix match.
ROA: RPKI origin-validation status by address-space share: valid, no ROA/not-found, or invalid.
ASPA: Share of ASes in the customer cone with a published RPKI ASPA object versus no ASPA. Each AS counts once.
Prepend: Address-space share whose observed announcement included AS-path prepending. The tree removes prepends before building hierarchy, but this metric keeps the traffic-engineering signal visible.
Default: Commodity-only probe result. Green means Full Table; neutral means Uses Default, where the response behaves as if commodity has only a default route.

Custom graph

Search jumps to an AS by ASN, name, holder, IP address, or prefix.
Filter builds a graph from a regex over prefixes, prefix holders, or ASNs in paths.
Prefixes builds a graph from one or more CIDR blocks and includes routes contained by those blocks.
Project resources builds a graph around routes tied to a selected project — measurement fleets (NRP, CAIDA Ark, RIPE Atlas, perfSONAR) or community-managed resources (NetSage Science Registry, OSG/OSPool, EGI).
Anycast opens the subset of routes whose prefixes are tagged as anycast.
Show matches lists matching routes even when the set is too broad to draw clearly. Open graph draws the focused graph when the direct Internet2-peer count is within Max peers.

Route class tabs draw canned graphs: Project resources, Anycast, Bogons (unregistered ASNs/prefixes), Private ASNs (leaked RFC 6996 private-use ASNs), and Tier-1 (routes transiting a settlement-free-clique Tier-1).

About the RE Topology Report

The RE Topology Report visualizes the Research & Education routing topology that converges on Internet2's AS11537. It's built from a snapshot of every BGP route received by Internet2 from its eBGP neighbors — pre-policy, so you see what neighbors announce, not just what Internet2 chose to install. Both accepted routes (those that passed Internet2's import policy and ROV) and rejected routes (those that violated policy and were filtered) are kept and labelled, so you can see the full set of paths neighbors offer to Internet2 and where filtering happens.

The data

BGP routes — a snapshot of every pre-policy route received by Internet2 (AS11537) on each of its eBGP sessions. Each route carries a prefix, an AS-path, and a flag indicating whether Internet2's import policy accepted or rejected it. Consecutive duplicate ASes in the AS-path (path-prepending) are collapsed before aggregation.
AS organization names — CAIDA's as-org2info dataset, refreshed every 24h. Provides the friendly operator name shown next to each AS number (e.g. AS3356 — Level 3 Parent, LLC).
RIPE Stat fallback — for ASes that CAIDA's join doesn't cover (LACNIC and AFRINIC coverage in the CAIDA dataset is historically spotty), the report queries RIPE Stat's as-overview and whois endpoints and uses the resulting holder string. RIPE Stat aggregates whois from every RIR.
Prefix holder names — RIPE Stat whois with an ARIN RDAP fallback chain (rdap-bottom → /registry/ip/), used to populate the holder column in the per-AS prefix lists. Lookups are cached at 24h ± 4h so repeat builds don't re-hit the upstream services.

The tree (front page)

The front page is a hierarchical tree of every AS that appears in any AS-path Internet2 received. The root is AS11537; its direct children are Internet2's eBGP neighbors; their children are the next AS in those neighbors' paths; and so on down to the origin AS that announced each prefix.

Click the ▶ toggle on a row to expand its sub-tree; click again to collapse.
Select the AS pill (the AS… — name chip) to open the focused Sankey view for that AS.
The two numeric columns (right-aligned, alternating background) show, for the AS at that tree position:
- Accepted — count of distinct prefixes whose path traverses this AS and that Internet2 accepted into its forwarding table.
- Rejected — count of distinct prefixes whose path traverses this AS but that Internet2 rejected (RPKI invalid, ASPA invalid, IRR mismatch, etc.).
Tooltip on each numeric cell adds the originated count when the AS is itself the origin (e.g. “1,243 accepted prefixes through AS3356 (12 originated here)”).

The Sankey view (focused mini-DAG)

Selecting an AS takes over the full window with a layered Sankey diagram of every distinct AS-path the focused AS uses to reach AS11537; the ← All ASes arrow at the top-left returns to the tree. The diagram is a Sugiyama-style DAG — left-to-right layering, dummy nodes inserted on long edges so ribbons stay monotonic and crossings are minimised by a barycenter sweep.

The focused AS sits on the left (orange) and AS11537 on the right (blue, with a fixed minimum height so the accepted/rejected split is always readable). Every intermediate AS sits in its own column between them.
Ribbon thickness at any cross-section is proportional to the number of prefixes flowing through that edge.
Accepted-route color identifies the last-hop AS into AS11537 — that is, the Internet2 neighbor that handed the route over. Every ribbon along a single end-to-end path keeps the same colour so you can trace it visually. Rejected routes are always red.
AS11537's bar is split into an accepted band (top, blue) and a rejected band (bottom, red). Band heights are sized by prefix-flow deliveries across paths, and the label inside each band also shows the unique-prefix count.
Inside each band, prefixes group into blocks by signature: prefixes announced via the same set of upstream ASes (or paths, for rejected) form one block at a fixed y-offset. Strands from different sources to the same block target the same y, so shared prefixes overlap visually as multiple coloured ribbons stacked at one point. That's the one-glance multi-path indicator at the destination.
Hover any ribbon to see the from→to ASNs, source AS, prefix count, and (for shared blocks) which other ASes carry the same prefixes. Click an AS bar to open a route-table modal listing every prefix that flows through it, with holder names and full AS-paths.
The view fills the whole window so wide Sankeys read without a cramped side panel; the ← All ASes arrow (or Esc) returns to the tree. The topology always shows every route in the focused AS's customer cone seen by Internet2.
The URL hash #asn=NNN tracks the focused view, so any panel state is a shareable link.

Search

The search box accepts an AS number (AS27343 or just 27343), a partial AS name, an IP address, or a prefix (192.0.2.0/24). IPs and prefixes are matched with longest-prefix match against every announced prefix in the report, so you can drop in any IPv4 or IPv6 address and jump to the AS that originates its covering prefix. Activating a result opens the Sankey panel for that AS.

Attribution

This tool is part of the ROOTBEER (Routing Operations Observational Technology: Building to Enable Education and Research) suite, a joint effort between Internet2 and CAIDA (the Center for Applied Internet Data Analysis at UC San Diego). Internet2 contributes the BGP route snapshots and operational policy context; CAIDA contributes the AS-organization, AS-relationship, and topology datasets that power the rest of the suite.

This material is based on research sponsored by the National Science Foundation (NSF) grant OAC-2530871. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of NSF.

Report status — freshness

Each row below shows when this report's view of that upstream feed was last refreshed. The BGP-route fetch runs once at process startup; per-session entries older than 72 hours are evicted from the on-disk cache.

Source	Last refreshed	Items	Notes